Pump unit



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UnitedStates Patent PUMP UNIT Heinrich K. Links, Stuttgart, Germany, assigner to Daimler-Benz Aktiengesellschaft, Stuttgart-Unterturkheim, Germany Application May 23, 1951, Serial No. 227,763

Claims priority, application Germany May 23, 1950 3 Claims. (Cl. 103-4) The invention relates to a pump unit, particularly to a pump unit with a fuel feed pump for injection combustion engines, wherein the fuel feed pump is secured to the injection pump of the engine at the camshaft of the latter.

An object of the invention is a simple, reliable drive and a good accessibility of the feed pump.

An important characteristic of the invention resides in the fact that the pump feed member respectively the drive push rod of the same is arranged co-axially with the driving shaft and acts together with the latter through axial projections in such a manner that upon turning of the shaft the pump feed member performs a reciprocating motion in the axial direction of the shaft.

In the drawing a diaphragm pump is represented as an example of construction of the invention, Figure l showing one part of the injection pump in side view with the attached feed pump in longitudinal section and Figure 2 showing the inner end of the piston push rod of the feed pump itself.

The camshaft 5 of the injection pump 6, which is driven by a gear wheel jackshaft system at its front end and which is not illustrated herein, moves the pistons 8 of the injection pump up and down in the known manner by means of cams 'i' on shaft 5. An auxiliary housing @n is attached to the left of the injection pump housing 6 in any conventional manner, as, forrexample, by means of machine screws 30 and 31. The auxiliary housing 6a may contain, for example, the regulator mechanism, as is well known with such type of fuel injection pumps. To the outward end of the injection pump, away from the driving side, and below the auxiliary housing 6a the fuel feed pump 9 is attached coaxially with the camshaft 5 by means of a connection 10.

The feed pump 9 is constructed in a manner, which is known in itself, as a diaphragm pump, wherein the axially reciprocating diaphragm 11 sucks the liquid fuel from a supply tank into the pump space 12 and conveys it from there to the cylinders of the injection pump 6. By means of one suction and of one delivery valve, which is arranged in the pump space and which is not illustrated herein, the supply and delivery of liquid is thereby automatically effected in the known manner.

The diaphragm 11 is on the side of the pump space 12 loaded with an initially stressed helical thrust spring 13. On the opposite side it is guided axially slidably on a hollow tenen-like central projection 15 by means of a hoilow piston-like sleeve 14, which is attached to it.

The piston push rod 16 of the pump, which is slidingly guided the projection 15, rests with its extreme end 16a in ail pump positions firmly against the bottom 14a of the sleeve lf3. The hollow piston-like widened inner end 17 of the push rod 16 is loosely slidable upon the free end i8 of the camshaft 5, so that both parts can freely rotate relative to each other. The piston-like end i7 of the push rod 16 is provided atits face 17 with niches 20 (Figure 2), which are arranged diametrically opposite to each other, and which form a cam, which ,n 2,737,893 Plitented4 Mar. 13,- 1956 lCC runsl approximately in accordance' with a sinusoid; by means of which the push rod 16' is'supported" ontwo pressure rolls 21, which are radially arranged on the camshaft 5. The latter are pivoted on a pin or bearing bolt 22, which passes transversely through the camshaft, and are secured against displacement towards the outside by washers 23, which engage in grooves in pin 22. The bearing bolt 22 is held in the camshaft by a screw 24, which engages with its end 25 a flattened portion provided on the bolt 22.

As a result of the pressure spring 13 the guide bearing 14, which is attached to the diaphragm 11, is kept in constant pressure connection with the outward end of the piston push rod 16, and the cam face 19 of the piston push rod is kept in constant pressure connection with the pressure rolls 2l, so that the piston push rod 16 and with it the diaphragm 11 is moved twice to and fro in the axial direction with each rotation of the camshaft, in order to achieve the intended pump effect in the space 12. In order to prevent in this connection that the piston push rod turns along with the camshaft 5, the piston-like part 17 of the push rod is additionally guided by a pin 26, which is supported by the connection 10, which is located eccentrically to it, and which engages into a semi-cylindrical recess 27 of the part 17.

An extremely simple and speedy assembly and disas sembly of the feed pump and its parts is made feasible by the present invention. The practicability of the invention is in this connection not restricted to the represented form of construction. Thus the cam surface 19 can for example also be carried by the camshaft 5 and the pressure rolls 21 carried by the piston push rod 16. Also the cam track at the surface 19 can have any other than the represented sinusoidal formation, for example in the form that the diaphragm of the feed pump with every rotation of the camshaft 5 is reciprocated one or more times per revolution of the shaft 5. The pump can be constructed as a diaphragm or piston pump or in any other manner as a reciprocating pump.

What I claim is:

l. A pump unit for internal combustion engines cornprising a rotary pump drive shaft, radial cams on the pump drive shaft, injection pump pistons actuated by the said cams, a cylinder housing, cylinders for said injection pump pistons arranged in said cylinder housing substantially perpendicular to the pump drive shaft, an auxiliary housing carried by said cyl'mder block and extending outwardly beyond the latter, said auxiliary housing enclosing the regulator mechanism for the injection pump formed by said injection pump pistons and cylinders, a feed pump element supported on said cylinder housing below said auxiliary housing reciprocable in a direction parallel to the axis of said shaft, a reciprocable push-rod arranged parallel with respect to the shaft and arranged for driving the reciprocating pump element, driving means between said shaft and said rod comprising two rollers carried by said shaft and at least one cam-like projection on said push-rod whereby said reciprocable pump element is reciprocated in the axial direction of the shaft upon rotation of the shaft while said pistons are reciprocated transversely to said shaft.

2. The combination according to claim l, together with means for preventing rotation of said push-rod member.

3. The combination according to claim 1, together with means for preventing rotation of said push-rod member, said means comprising a pin carried by said cylinder housing extending parallel to said shaft and received in a recess in said push-rod member.

(References on following page) References Cited in the le of this patent Metcalfe Mar. 16, 1926 Babitch Nov. 29, 1932 Hedblom July 9, 1935 4 Deschamps Sept. 15, 1942 St'n'1ey"` Feb. 6, 1951 Hoier June 12, 1951 FOREIGN PATENTS Sweden 

